<!doctype html>

<title>04 Components - React From Zero</title>

<script src="https://unpkg.com/react@15.4.2/dist/react.js"></script>
<script src="https://unpkg.com/react-dom@15.4.2/dist/react-dom.js"></script>
<script src="https://unpkg.com/babel-core@5.8.38/browser.min.js"></script>

<div id="app"></div>

<script type="text/babel">

// The main selling point of React is its component system
// components are used to encapsulate elements and their behaviour
// see them as a mix of controller and view of MVC

// Here we use stand alone elements and some data
var data = 'world'
var reactElement =
  <div>
    <h1>Hello</h1>
    <h2>{data}</h2>
  </div>

// Here the elements are encapsuled in a simple component function
// They have to start with a capital letter and
// return exactly ONE root element with or without nested elements
function MyComponent() {
  var data = 'world'
  return (
    <div>
      <h1>Hello</h1>
      <h2>{data}</h2>
    </div>
  )
}

// a component function can be used like an element
reactElement = <MyComponent/>

// this translates to a React.createElement() call
// the null indicates that no properties have been set
reactElement = React.createElement(MyComponent, null)

//  for reference a react-internal <div> tag
var anotherElement = <div/>
// gets converted to
anotherElement = React.createElement('div', null)

var renderTarget = document.getElementById('app')

ReactDOM.render(reactElement, renderTarget)

</script>